Reductive electrosynthesis of crystalline metal-organic frameworks

Electroreduction of oxoanions affords hydroxide equivalents that induce selective deposition of crystalline metal–organic frameworks (MOFs) on conductive surfaces. The method is illustrated by cathodic electrodeposition of Zn[subscript 4]O(BDC)[subscript 3] (MOF-5; BDC = 1,4-benzenedicarboxylate), which is deposited at room temperature in only 15 min under cathodic potential. Although many crystalline phases are known in the Zn[superscript 2+]/BDCsuperscript 2–] system, MOF-5 is the only observed crystalline MOF phase under these conditions. This fast and mild method of synthesizing MOFs is amenable to direct surface functionalization and could impact applications requiring conformal coatings of microporous MOFs, such as gas separation membranes and electrochemical sensors.Massachusetts Institute of Technology. Energy Initiative (Seed Fund Program)National Science Foundation (U.S.) (Grant CHE-9808061)National Science Foundation (U.S.) (Grant DBI-9729592)National Science Foundation (U.S.) (Grant DMR- 0819762

Divalent Heteroleptic Ytterbium Complexes – Effective Catalysts for Intermolecular Styrene Hydrophosphination and Hydroamination

New heteroleptic Yb­(II)–amide species supported by amidinate and 1,3,6,8-tetra-<i>tert</i>-butylcarbazol-9-yl ligands [2-MeOC₆H₄NC­(<i>t</i>Bu)­N­(C₆H₃-<i>i</i>Pr₂-2,6)]­YbN­(SiMe₃)₂(THF) (<b>6</b>) and [1,3,6,8-<i>t</i>Bu₄C₁₂H₄N]­Yb­[N­(SiMe₃)₂]­(THF)_<i>n</i> (<i>n</i> = 1 (<b>7</b>), 2 (<b>8</b>)) were synthesized using the amine elimination approach. Complex <b>6</b> features an unusual κ¹-<i>N</i>,κ²-<i>O</i>,η⁶-arene coordination mode of the amidinate ligand onto Yb­(II). Complexes <b>7</b> and <b>8</b> represent the first examples of lanthanide complexes with π-coordination of carbazol-9-yl ligands. Complexes <b>6</b> and <b>7</b>, as well as the amidinate–Yb­(II)–amide [<i>t</i>BuC­(NC₆H₃-<i>i</i>Pr₂-2,6)₂]­YbN­(SiMe₃)₂(THF) (<b>5</b>), are efficient precatalysts for the intermolecular hydrophosphination and hydroamination of styrene with diphenylphosphine, phenylphosphine, and pyrrolidine to give exclusively the anti-Markovnikov monoaddition product. For both types of reaction, the best performances were observed with carbazol-9-yl complex <b>7</b> (TONs up to 92 and 48 mol/mol at 60 °C, respectively)